update setup.cfg

Author: thoo

Diff for: setup.cfg

@@ -336,9 +336,6 @@ skip=
     pandas/tests/arrays/categorical/test_missing.py,
     pandas/tests/arrays/categorical/test_api.py,
     pandas/tests/arrays/categorical/test_constructors.py,
-    pandas/tests/util/test_testing.py,
-    pandas/tests/util/test_util.py,
-    pandas/tests/util/test_hashing.py,
     pandas/tests/extension/test_common.py,
     pandas/tests/extension/test_integer.py,
     pandas/tests/extension/test_external_block.py,